At the time of the Targaryen Conquest, the last King of the Mountain and the Vale was a young boy, Ronnel Arryn, so the Vale was ruled on his behalf by his mother, Queen RegentSharra Arryn. Ultimately Visenya Targaryen flew over the guarded mountain passes on her dragon, Vhagar, directly to the Eyrie. Visenya did not burn the castle, and when the young King Ronnel came out to meet her in the courtyard he asked if she would give him a ride on her dragon, and she agreed. When Sharra arrived and saw her son in Visenya's lap on the dragon, the implicit threat was enough to make her surrender the castle.

In the A Song of Ice and Fire novels, the history of the Kingdom of Mountain and Vale is the same. However, during the rule of House Arryn, which had ended the line of the Mountain Kings, the kingdom was renamed the Kingdom of Vale and Sky.